Correcting a droopy bay

Following on from the scaffolding thread....one of the jobs on the very long list is to look to improve our main bay.

Its a 1930s place with approx 5m square bay, at some point, probably when the windows were replaced the bay has drooped noticably.  Structural survey said its pretty common and not an issue.

But, it looks rubbish and despite having the guttering moved as high as it will go, I have a lovely water feature when the rain is really heavy as the guttering overflows and creates a waterfall.

Is it possible to jack the bay up and put some supports in there, I've seen a few places local with wood triangles supporting the roof overhang

If its a massive pain in the butt, I will probably just get it sorted when we eventually have to re-roof, as we are still on the original roof (which is holding up fine, but its nearing end of expected life)

Anyone had this job done?  How did the builders do it, and how long / how much did it cost?